Apparatus for solvent extraction



March 23,1937. 'w'J. O'BRIEN ET AL I APPARATUS FOR SOLVENT EXTRACTIONFiled July 2.1, 1934 a ma v Patented Mar. 23, 1937 UNITED STATESAPPARATUS FOR SOLVENT EXTRACTION William J. O'Brien and Roy 0. Brett,Cleveland,

Ohio, assignors to The Glidden Cleveland, Ohio, a corporation of OhioCompany,

Application July 21, 1934, Serial No. 736,288

3 Claims. (Cl. 87- 6) This invention relates toa process and apparatusfor extraction and recovery by means of solvents, and has particularreference to the extraction and recovery from oiland fat-bearingmaterials, such as cotton seed, sun flower seed, soy bean and othersimilar substances by the use of volatile solvents.

The methods heretofore employed for,the extraction of oils and fats bybatch or continuous operation have embodied agitation of the materials,filtration of the solvents and decantatlon of the liquors carryingvarious quantities of the extracted substances.

Among the objects of this invention is the pro- Vision of a method andmeans whereby the ex traction and recovery may be carried out withgreater economy and eiiiciency than heretofore practised and at the same'time effect such extraction at temperatures below that at which damagewould result to the extract itself or to any of the other constituentsof the material subjected to extraction where it is desired to preservethe characteristics and qualities of such constituents.

A further objectof this invention is the prcvision of a process andapparatus whereby ap-- propriation may be made of the advantages whichwe have found are to be derived from subjecting-the material during theextraction to certain stages 'of treatment and in certain sequence.

More specifically, it is an object of this invention to provide a methodand means for utilizing the special advantages heretofore set forth inthe extraction and recovery of oils and fats from 'oiland fat-bearingmaterials, particularly soy beans, sun flower seeds, cotton seeds, etc.

Other, further and more specific objects of this invention will'becomereadily apparent to persons skilled in the art from a consideration ofthe following description when taken in conjunction with theaccompanying drawing wherein We. have illustrated diagrammatically andin section a specific embodiment of the apparatus embraced in ourinvention. This apparatus comprises the vessel or chamber I having afrusto-conical bottom 2 from which the neck 3 serves as an outlet andmeans of communication with the other vessel or chamber E. A substantialportion of this chamber 4 is sur- 0 rounded by the jacket 5 throughwhich suitable heating or cooling fluid may be circulated for thepurpose of maintaining effective and proper temperature of theextraction solvent which is supplied through the pipe 6 and passesdownwardly through the chamber 4 and then upward ly in chamber i. Asillustrated in the drawing, in our preferred embodiment, 'the chamber lis vertical while chamber 4 is obliquely inclined thereto.

The chamber l is provided with a plurality of 5 agitators or stirrers Iand 8 which are attached to the spindle 9, driven by the gear I!)connected to a suitable source of power. At the top of the chamber l thematerial to be extracted enters through the hopper II and isprogressively fed by 10 the spiral conveyor I 2, operated by the gear l3connected 'to a suitable source'of power.

An important feature of this invention is the special means we haveprovided for carrying solid material from the bottom ofthis chamber 4 15onward to the top and subjecting this material to progressive stages ofcompression as it reaches the outlet at the top of this chamber 4. Thisspecial means comprises the spiral conveyor I4, the spirals of whichhave a uniform pitch from 20 the bottom to the point l5, but from thepoint l5 to the top thespirals gradually diminish in pitch. While solidmaterial is traveling through the portion of the conveyor where thespirals are of uniform pitch there will be practically no com- 25pression, but on reaching the spirals of gradually diminishing pitch thecompression will begin and gradually increase toward the outlet. Furthercompression of the material before reaching the outlet of the chamber 4is brought about by the inverted frusto-conical member l6 which fitsinto the upper part of the chamber 4 and makes the approach to theoutlet of the vessel 4 of gradually decreasing cross-section. Theconveyor l4 and member l6 are rotated by the gear l1 connected to asuitable source of power. The source of power forthe gear H as well asthose for gears l0 and. I3 should allow a sufiicient range of speeds ofthese gears to meet the needs of operation.

In carrying out our extraction process, the ex- 40 tracting solvent isintroduced through the inlet 6 and flows down the chamber 4' through theneck 3 and then upward through the chamber I to "the level A. An outleti8 is provided at this level. The material to be extracted is fed fromthe hopper ll, drops to the surface of the solvent in the chamber i andgradually proceeds to the bottom of this chamber, forming a deep columnthrough which the liquid is forced upwardly by the hydrostatic head ofthe solvent from the chamber 4. It will be noted that the solvent entersthe-chamber 4 at approximately the level of A in chamber I.

We have found that superior results are ob- .tained if, instead of thesolvent passing upward 55 1 through a continuous column of the materialto i be extracted, it is passed through alternate zones of condensationandrarefaction of this material. This is accomplished'by means ofmultiple-arm 5 agitators I and 8. When these agitators are in operation,the material to be extracted and lying in the. zone C to D and the zonefrom E to the bottom which constitute the immediate vicinities of theseagitators will be in a state of agitation and also rarefied instead. ofconcentrated and quiescent as is'the material in zones B to C and D to Ewhich are remote from these agitators or stirrers. Consequently whenoperating these stirrers,

alternate zones of condensation and rarefaction of the material to beextracted are formed of the materlal undergoing extraction and thesolvent will pass through these alternate zones against dif-'- ferent'resistances to its upward flow. We have found that more effectiveextraction is produced under these conditions.

We desire to have the distance between the agitators or stirrers ofsuflicient length to permit the formation of a column of the material inthe zones of concentration and having enough depth to afiord a filteringmedium to the solvent passing therethrough as well as supplying materialfrom which one or more constituents are to be extracted. In the upperzone from A to B the material undergoing extraction is more rarefiedthan in zones B to C and D to E.

In the specific illustrations we have shown twoagitators but it is to beunderstood that any other number may be employed within the spirit andscope of this invention. Also, these agitators may be made adjustablewith respect to location and angular direction, so that by properpositioning of the blades of the stirrers and regulation of the speed,the rate of feed of the solid material from zone to zone may beregulated and con- 40 trolled.

be completely washed and the extraction completed. As the'residue movesfurther upwardly beyond the point l5, it will be engaged by the spiralsof gradually diminishing pitch and will be subjected to compression andthe liquid will be I gradually forced therefrom. More liquid will beexpressed when this material is forced between the wall of the chamber 4and the frusto-conical member l6 so that on reaching the top outlet ofthe chamber 4; most of the solvent will have been '60 removed from thesolid material.

The quantity of liquid entering the chamber 4 is controlled by means ofa valve l9 su ably located in the feed line 6. Wit-hin the cham r Ithere is provided a screen-20 of suitable mesh to prevent the solidmaterial passing out with the supernatant liquor through the outlet l8.

In carrying out this invention the material to be extracted is firstprepared to permit a maxi- I mum penetration of the solve'nt and toeliminate as far as possible the objectionable condition of v fines.

In using our processior the extraction of oils from soy beans, sunflowerseeds and cotton seeds,

the specially prepared material to be extracted is first tedcontinuously onto the surface A of the 7 complete extraction of theoils. of the material to be extracted through the two preparing thematerial for effective extraction of the oil as the material passesthrough diminishing concentration of oil and solvent liquor. The slowprecipitation of the material through this. miscella zone A-B tends toincrease the concentration of oil in the miscella before decantation.

Second, the material is allowed to lie quiescent in the zone 13-0 toafiord complete saturation, and in this zone the material to beextracted serves as a flnal leaching bed through which the liquors rise.The relatively slow upward movement of the oil-solvent liquors does notdisturb the fines entrapped by coarse particles of material beingextracted, thus permitting a substantially clear miscella to bedecanted.

Third, the material is gently agitated in the zone C--D before enteringthe second or initial Quiescent zone D-E by the agitator I to cause theliquors to ascend in a somewhat spiral path thus substantially avoidinga straight line path of travel. This gentle agitation also tends toexpedite the extraction of the oils.

Fourth, the material is again allowed to remain in a quiescent state forfurther saturation of weaker oil-solvent liquors as said liquors slowlypass up through their initial quiescent zone Fifth, the material isagain agitated by the agitator 8 which not only agitates the material toprevent a substantially straight line flow oi lesser concentratedoil-solvent liquors but also discharges the material into 'the cleansingorv Washing zone in chamber 4 after the oil has been substantiallydifiused and displaced from the cellular structure. This insuressubstantially The movement quiescent zones is eflected'by gravity.

Sixth, the material is now slowly conveyed up through a counter-currentfiow of clear preheated solvent thus eifecting a thorough washing of thematerial with fresh solvent, the latter being introduced at or near thedischarge point of the extracted material justbefore the extracted ma.-terial is subjected to a zone of pressing or squeezing action to removesubstantially all of the solvent. This solvent is fed into theextractorunder sufllcient hydrostatic head to overcome the doubleleaching bed' resistance to control the flow of solvent so as toaccomplish substantially complete and eflicient extraction and to eilectcounter-current travel without substantially ailect-.

ing the efiectiveness oi the pressing or squeezing action.

Seventh, the extracted material is now sub- I jected to a zone ofcontinuous pressing or squeezing in the upper part of chamber 4 tosubstantially free the extracted material of excess solvent beforeentering a suitable heated drying apparatus (not shown) for removing andrecovering the balance of solvent in the extracted material; The dryingapparatus may be any suitable standard equipment and, although an tionof the oils with solvent and sets up in a suitable apparatus a mosteffective method oi! accomplishing substantially complete extraction ofmaterials economically and without affecting the suitability of theextracted material for other products.

Since the carrier of the extracted oils is solvent, sufficient time mustbe allowed for the solvent to penetrate the cellular structure of thevent in the extracted material. Also, the introduction of solvent and ofthe material to be extracted and the removal of'the liquor carrying thesubstances extracted and oiv the expressed residue are accomplishedunder conditions whereby escape of vapors from the solvent is r'erlucedsubstantially to a minimum.

Although in the specific illustration we have set forth the extractionof fats and oils from oleaginous materials, it is to be understood thatthe apparatus and process herein set forthvand described are adapted tothe extraction and recovery of various other products and materials aswell as by-products,'when so desired. This invention may also be adaptedto the treatment of materials of different specific gravity than theoleaginous materials herein set forth and also to the use of solvents ofdifierent specific gravity than those commonly employed for extractingthe oleaginous materials specifically set forth herein I The presentinvention is not limited to the specific details set forth in theforegoing examples which should be construed as illustrative,

and not by way of limitation, and in view of the numerous modificationswhich may be effected therein without departing from the spirit andscope of this invention, it is desired that only such limitations beimposed as are indicated in the appended claims.

We claim as our invention:

1. In an apparatus for extraction by means of a solvent, a chamberhaving an inlet for material bearing the substance-to be' extracted anda plurality of agitators. vertically spaced from each other to providealternate zones of condensation and substantial quiescence and zones ofrarefaction and mild agitation of said material, a

second chamber having its lower portion in communication with the'firstchamber, one of said agitators being of multiple-arm construction anddisposed immediately adjacent to the bottom of the first chamber and thepassageway from said first chamber to said second chamber so that whenrotated the ends of said arms will cut across said passageway andthereby agitate and force the material from said first chamber into saidsecond chamber, said second chamber comprising an upwardly-extending,elongated passageway, a spiral conveyor within said elongated passagewayand disposed to convey material from the bottom of the first chamberupwardly through said elongated passageway, and means for introducing asolvent in said second chamber below the outlet from said secondchamberfor the residue from the material subjected to ex traction, said spiralconveyor having an upper portion of the spirals of gradually recedingpitch at the outlet for said residue to force solvent associatedtherewith back into said second chamber.

2. In an apparatus for extraction. by means of a solvent, a chamberhaving an inlet in the upper portion for material bearing the substanceto be extracted and a plurality of adjustable agitators verticallyspaced from each other to pro-.

'chamber and having its lower portion in communication with the firstchamber, one of said agitators being of multiple-arm construction anddisposed immediately adjacent to the bottom of the'first chamber and thepassageway from said first chamber to said second chamber so that whenrotated the ends of said arms will out across said passageway andthereby agitate and force the material from said first chamber into saidsecond chamber, said second chamber comprising an upwardly-extending,elongated passageway, a spiral conveyor within said elongated passagewayand disposed to convey material from the bottom of the first chamberupwardly through sai elongated passageway, and means for introducing asolvent in said second chamber be from each other to provide alternatezones of condensation and substantial quiescence and zones ofrarefaction and mild agitation of said material, a second chamber havingits lower portion in communication with the first chamber, one of saidagitators being of multiple-arm construction having a configuration sothat its path of revolution is in close conformity with the bottom ofsaid first chamber and disposed immediately adjacent to the bottom ofthe first chamber and the passageway from said first chamber to saidsecond chamber so that when rotated the ends of said arms will cutacross said passageway and thereby agitateand force the material fromsaid first chamber into said second chamber, said second chambercomprising an upwardly-extending, elongated passageway, a spiralconveyor within said elongated passageway and disposed to conveymaterial from the bottom of the first chamber upwardly through saidelongated passageway, and means for introducing'a solvent in said secondchamber below the outlet from said second chamber for the residue fromthe material subjected to extraction, said spiral conveyor having anupper portion of the spirals of gradually receding pitch at the outletfor said residue to force solvent associated therewith back into saidsecond chamber.

WILLIAM J. OBRIEN. ,ROY c. BRETT.

